1. Technical Field
The present invention generally relates to light emitting diodes.
2. Description of Related Art
Light emitting diodes (LEDs) as solid-state illuminating apparatuses, are being widely used in the illumination field to substitute for conventional fluorescent lamps due to their high brightness, long service lifetime, and wide color gamut. Relevant subject matter is disclosed in an article entitled “Solid-State Lighting: Toward Superior Illumination”, published in Proceedings of the IEEE, Vol. 93, No. 10, by Michael S. Shur et al. in October, 2005, the disclosure of which is incorporated herein by reference.
Referring to FIG. 5, a typical white light LED 10 includes a reflective cup 11, a LED chip 12, and an encapsulant 13 configured for encapsulating the LED chip 12. The reflective cup 11 includes a receiving groove 110, a positive electrode 111, and a negative electrode 112. The LED chip 12 is placed on a bottom 1102 of the receiving groove 110, and a side wall 1104 of the receiving groove 110 surrounds the LED chip 12 to collect light from the LED chip 12 and redirect it to an opening 1106 of the receiving groove 110. The opening 1106 of the receiving groove 110 is opposite to the bottom 1102. The positive electrode 111 and the negative electrode 112 are used to contact a power source (not shown). The LED chip 12 is position on the positive electrode 111 and is wire bonded to the negative electrode 112. The encapsulant 13 is doped with a plurality of phosphor particles 132, and is positioned in the receiving groove 110, and the phosphor particles 132 are deposited on the LED chip 12 to surround it. Thus, the phosphor particles 132 can be excited by blue light from the LED chip 12 to emit yellow light, and white light can be formed by mixture of the yellow light and the residuary blue light. The phosphor particles 132 surrounds the LED chip 12, thereby improving the light uniformity and the mixing light efficiency of the white light LED 10. However, the temperature of the LED chip 12 is usually high e.g. above 80° C., resulting decrease of the converted efficiency of the phosphor particles 132.
What is needed, therefore, is a light emitting diode with good light uniformity, which can overcome the above-mentioned disadvantages.